This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-222562, filed Aug. 5, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a flat display device represented by liquid crystal display devices.
Modern flat display devices, which are represented by liquid crystal display devices, are thin, light in weight, and highly power-efficient. Taking advantages of these features, they are utilized as various display devices for TV sets, computers, car navigation systems, etc.
In general, a liquid crystal display device of the light transmission type, for example, comprises a liquid crystal display panel, which includes a liquid crystal layer held between a pair of substrates, and a surface light source unit put on one surface of the display panel. The liquid crystal display panel and the surface light source unit are placed on a substantially rectangular resin frame. Overlying the display panel, a metallic bezel in the form of a rectangular frame is attached to the resin frame. Thus, the display panel and the light source unit are held between the frame and the bezel. Furthermore, the liquid crystal display device comprises a drive circuit board for supplying signals for driving the liquid crystal display panel. This drive circuit board is attached to the resin frame and opposite to a rear surface of the surface light source unit.
Typically, one end of the drive circuit board is located adjacent to side edges of the resin frame and bezel and is fixed thereto by using screws to tighten it with the resin frame and bezel. The other end of the drive circuit board is opposed to an intermediate portion of the resin frame and is fixed thereto by using screws to tighten it with the resin frame if the resin frame has a margin in thickness. On the contrary, if the resin frame has no margin in thickness, the other end of the drive circuit board is fixed to the resin frame using a double-sided adhesive tape.
In particular, modern liquid crystal display devices are expected to be thinner and lighter in weight due to market trends or in behalf of enclosures, and the resin frame, the metallic bezel, and the drive circuit board all have a tendency toward thinness. If both ends of the drive circuit board are fixed using screws, the substrate will be strong enough to withstand external impacts, but the liquid crystal display device entirely becomes thicker, thereby hindering attempts to reduce the thickness and weight.
Alternatively, if one end of the drive circuit board is fixed to the resin frame using the double-sided adhesive tape, the drive circuit board will be readily affected by external impacts or vibration and may slip out easily from the resin frame. If the drive circuit board slips out, a flexible printed circuit board electrically connecting the liquid crystal display panel and the drive circuit board together will be open-circuited to cause inappropriate displays or an optical sheet of the surface light source unit will be deflected to cause inappropriate displays. Furthermore, with the double-sided adhesive tape, the surface light source unit may contribute to making luminance irregular and lower the efficiency of assembly operation and repairability.
The present invention has been contrived in consideration of these circumstances, and its object is to provide a flat display device capable of being reduced in weight and thickness, enabling a drive circuit board to be reliably fixed so as not to be affected by external impacts or the like, and enjoying improved efficiency of assembly operation and repairability.
In order to achieve the above object, a flat display device according to the present invention comprises a substantially rectangular flat display panel having an effective display region, a substantially rectangular surface light source unit opposed to the flat display panel, a substantially rectangular frame carrying the flat display panel and the surface light source unit thereon, a bezel in the form of a substantially rectangular frame having an opening corresponding to the effective display region of the flat display panel and attached to the frame so that the display panel and the surface light source unit are held between the frame and the bezel, and a drive circuit board electrically connected to the flat display panel and opposed to the surface light source unit to supply signals for driving the flat display panel, wherein the frame has a projecting portion and the drive circuit board has an engaging portion held in engagement with the projecting portion.
In addition, according to the flat display device of the present invention, the projecting portion of the frame extends substantially parallel with the surface light source unit, and the engaging portion of the drive circuit board has an engaging projection inserted between the projecting portion of the frame and the surface light source unit.
Furthermore, according to the flat display device of the present invention, the projecting portion of the frame extends in a direction perpendicular to the surface light source unit, and the engaging portion of the drive circuit board has an engaging groove into which the projecting portion of the frame is fitted.
According to the liquid crystal display device constructed in this manner, the drive circuit board and the frame are connected and fixed together using the projecting portion provided on the frame, thereby allowing the drive circuit board to be easily fixed and repaired to improve operational efficiency. Additionally, this configuration provides an improved fixing strength sufficient to withstand external impacts, compared to the use of the double-side adhesive tape. This flat display device does not adversely affect the surface light source unit, enables the number of required screws to be reduced, and allows its weight and thickness to be diminished.
Consequently, by reducing the number of locations where the drive circuit board is screwed, a flat display device can be provided which is lighter in weight and thinner, which enables the drive circuit board to be reliably fixed so as to withstand external impacts or the like, and which enjoys improved efficiency of assembly operation and repairability.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.